1. Technical Field
The present disclosure generally relates to printed circuit boards (PCBs) and particularly, relates to a printed circuit board having shielding structure and a method for manufacturing the same.
2. Description of Related Art
PCBs are widely used in most electronic devices for mounting electronic components and providing electrical transmission. In some conditions, a shielding structure is needed on a surface of a PCB to provide protection against electromagnetic interference (EMI) generated by peripheral electronic components or devices.
The PCB usually comprises a grounded circuit layer and a protective layer formed on a surface of the grounded circuit layer. The grounded circuit layer comprises a connecting pad. The protective layer defines an opening and the connecting pad is exposed in the opening. One kind of well-known shielding structure includes an anisotropic conductive adhesive filled in the opening, a metallic deposition layer formed on the adhesive, an insulating layer, and a release film. The static electricity existing in the PCB can be guided to the metallic deposition layer and eliminated. The metallic deposition layer can also shield against EMI. Another kind of well-known shielding structure includes an electrically conductive adhesive filled in the opening and solder covering the adhesive. The adhesive can be silver glue. The static electricity existing in the PCB can be guided to the adhesive and eliminated.
However, demand for smaller PCB is growing, and so connecting pads are becoming smaller and smaller, and shielding structures are also becoming smaller and smaller. Thus, the amount of anisotropic conductive adhesive or electrically conductive adhesive that can be used has become so little reducing effectiveness.
What is needed, therefore, is a PCB and a method for manufacturing the same to overcome the above-described problems.